Internal combustion engines are equipped with a cooling system. The cooling system is generally provided for cooling down the internal combustion engine, as well as other engine fluids, such as for example the exhaust gas in the EGR cooler and/or the lubricating oil in the oil cooler. The cooling system schematically includes a coolant pump that delivers a coolant fluid, typically a mixture of water and antifreeze, from a coolant tank to a plurality of cooling channels. In some applications, the cooling system is split into two fluidically separate cooling circuits, one for the engine's cylinder block and one for the engine's cylinder head for example for optimizing engine warm up and improve fuel emissions.
An issue may arise due to the fact that, in the cooling circuit of the cylinder block, which is in a lower position with respect to the cooling circuit for the cylinder head, steam bubbles may be formed therein in case of boiling phenomena that may occur during operation of the engine. In general air bubbles could be present in the cylinder block cooling circuit and therefore could remain trapped within the cylinder block cooling circuit, especially in its upper portion and for this specific design.